With a P0340 OBD-II trouble code, diagnosis can be tricky at times. Here are some things to try:

• Visually inspect all the wiring and connectors in the circuit
• Check for continuity in the circuit wiring
• Check the operation (voltage) of the camshaft position sensor
• Replace the camshaft position sensor as required
• Check the crankshaft position circuit as well
• Replace circuit wiring and/or connectors as required
• Diagnose/replace the PCM as required

Credit
http://www.obd-codes.com/p0340

 

Thanks for some reason I didn't come across that one!

 

There is a modified cam sensor wiring loom for these.

 

The problem that you have Chris is that it sounds like an intermittent fault, an electricians nightmare. You cannot trace a fault that isn't there, so unless you are lucky enough to test when the fault is present, you could easily miss the problem and move on to other things.

The only real solution is to try and use a bit of common sense and keep your fingers crossed.

Remember that the sensor is only a small part of the complete circuit, so it could be a bad connection on any plug, or a break in any wire on the part of the loom involved. It could even be a faulty ECU component.

I would trace the complete circuit, from the sensor back to the ECU and check every connection (including the crimp) for any signs at all. Treat every connection to a good dousing of contact cleaner.

If you have exhausted every possibility then it may be worth having the ECU checked.

 

Did you get this sorted Chris? I have a P0340 comes on as pending every time I start up. It idles rough for a wee bit but once driven and warmed up, it goes away and code never becomes stored, its always pending and doesn't come back when cleared, until its left overnight and then restarted .

 

Bump...for Chris T

Sorry Broon didn't see your post beck in January, think I was too occupied with a new baby...

Did you get this sorted out? I am running out of options - bloody intermittent faults.

It now only seems to happen at very low speed - moving in or out of car park spaces, often in reverse. This is leading me to think that the sensor is picking up some vibration perhaps from the clutch.

 

Bump...for Chris T

 

I swapped the camshaft pos sensor over this one a while back and prob went away for a while, but came back with a vengeance during the bad weather. My guess is its actually a sensor mis-report brought about by condensation on the loom.

MIL goes away after a few engine restarts. Failing that ebay does any number of ELM based usb OBDII readers with free software that resets the MIL for under £20

 

The code is never stored and therefore never triggers the MIL

 

One thought...

on my 4x4 I can only read fault codes when ignition is in pos2, but once engine is running I can never read anything. (never found out why - its pre OBD2 and quite strange at the best of time)

That ALWAYS reports a cam sensor pending fail... but when you think about it, ignition in pos2 is always going to do that - ie the camshaft isnt spinning. Once it fires up the fault is gone, but next time I read from it, its back in a static pos2.

 

The cam pos data is probably one of the more critical feeds back to the ECU as far as non-corruption goes. It needs to be a nice clean square wave with a bit of a flutter at a couple of points during the rotation to give some key timing data to the ECU. If for any reason it has significant noise on the input then it is going to make things run rough. If you have access to an oscilloscope then scoping the input at the ECU can give you a good idea of whats going on. Whenever I checked it always looked clean - but of course it was not actually giving the fault when I checked - sods law.

The fact that I continued to see the same fault on Lyns TF after the sensor was changed, but only in very cold/damp conditions makes me pretty certain its condensation across some contacts. As commented that can be anywhere between the sensor and the ECU itself.

I remember when you could diagnose any car electrical problems with a spare sidelight bulb and a wet finger.... all this modern technolgy - where has it got us??

 

Its got jobs for autoelectricians :lol:

Cheers, wouldn't even know what to do with an oscilloscope if I had one. I will maybe just switch sensors just now as I have a spare one, then take it from there.

I have a very slippy /squeally alternator belt and a very wet drivers seat to deal with first

 

Well this problem continued to get worse in that the MIL would come on 20 to 30 seconds after the engine was started although it never affected the running of the car. Although not convinced that sensor was at fault (Hall Effect sensors tend either work or not) I was close to putting a new one on the engine.

However since fitting a new alternator on Saturday the problem seems to have gone away – time will tell but it could well have been signs of a failing alternator.